Outdoor luminaires, otherwise known as streetlights, are positioned to provide lighting for streets, pavements and other areas that need to be illuminated at night. Such luminaires are connected to a lighting dedicated switched mains network so that each luminaire is switched on during the hours of darkness and switched off during daylight hours as no power is supplied to the luminaire during daylight hours.
In modern outdoor lighting environments, additional functionality may be required, for example, non-lighting related loads, such as sensors, cameras, transmitters, etc., which need to be powered during daylight hours when the lighting dedicated switched mains network is switched off.
JP-A-2010-272495 describes an outdoor luminaire which includes non-lighting related load, such as a motion sensor associated with a crime prevention camera and a charging point for a mobile phone. A battery is used as a power source for the non-lighting related load so that power is supplied during the day when the luminaire is switched off. The battery is connected to a solar panel so that it can be charged during daylight hours and is available for providing power for non-lighting related load.
IN/2010DEL/02996 describes a power system for a luminaire in which a solar panel is used to charge a battery whilst the sun is shining, the stored energy from the battery being used for powering both DC lighting related loads and DC non-lighting related loads. In addition, an AC supply from a mains supply may be used to power AC lighting related loads as is conventional as well as non-lighting related loads.
WO-A-2010/057138 describes an energy-efficient solar-powered outdoor lighting system in which a solar panel mounted on a supporting pole of a luminaire generates electricity which is stored in a battery housed in the base of the luminaire or underneath the luminaire and from which battery energy can be provided for non-lighting applications, for example, to power light-emitting diode elements at night. Alternatively, the battery may be positioned at another suitable location and connected to the luminaire by underground wiring. Power from the batteries may be used to supplement the grid during hours of peak electricity usage as well as being used for powering non-lighting functions, for example, camera and/or recorder for a security system, wireless network radio, motion sensors and photocells.
Whilst the use of batteries is known for providing energy for non-lighting related loads, such batteries tend to rely on relatively expensive alternative energy supplies, such as solar energy, to be able to charge the batteries during daylight hours when power from the electricity grid is effectively switched off.
There is therefore a need to be able to provide power for non-lighting related loads during periods when power from the electricity grid is switched off, for example, in daylight hours, without having to implement expensive alternative energy systems, such as, solar energy systems, energy harvesting using piezoelectric systems and thermoelectric systems, and wind turbines etc.